Pipeline Design for Water Engineers: Third Revised and Updated Edition PDF
Preview Pipeline Design for Water Engineers: Third Revised and Updated Edition
THIRD REVISED AND UPDATED EDITION DAVID STEPHENSON Department of Civil Engineering University of the Witwatersrand Johannesburg, South Africa ELSEVlE R Amsterdam - Oxford - New York - Tokyo 1989 ELSEYIER SCIENCE PUBLISHERS B.V. Sara Burgerhartstraat 25 P.O. Box 2 1 1, 1000 A€ Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC. 655, Avenue of the Americas New York, NY 10017, U.S.A. ISBN 0-444-87373-2 0 Elsevier Science Publishers B.V., 1989 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science Publish- ers B.V./ Physical Sciences & Engineering Division, P.O. Box 330, 1000 AH Amsterdam, The Netherlands. Special regulations for readers in the U.S.A. - This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the USA. All other copyright questions, including photocopying outside of the USA, should be referred to the publisher. No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or opera- tion of any methods, products, instructions or ideas contained in the material herein. Printed in The Netherlands V PREFACE TO FIRST EDITION Pipelines are being constructed in ever-increasing diameters, lengths and working pressures. Accurate and rational design bases are essential to achieve economic and safe designs. Engineers have for years resorted to semi-empirical design formulae. Much work has recently been done in an effort to rationalize the design of pipelines. This book col lates pub1 ished material on rational design methods as well as presenting some new techniques and data. Although retaining conventional approaches in many instances, the aim of the oook is to bring the most modern design techniques to the civil or hydraulic engineer. It is suitable as an introduction to the subject but also contains data on the most advanced techniques in the field. i3ecause of the sound theoretical background the book will al so be useful to under-graduate and post-graduate students. Many of the subjects, such as mathematical optimization, are still in their infancy and the book may provide leads for further research. The methods of solution proposed for many problems bear in mind the modern acceptance of computers and calculators and many of the graphs in the book were prepared with the assistance of computers. The first half of this book is concerned with hydraulics and planning of pipelines. In the second half, structural design and ancillary features are discussed. The book does not deal in detail with manufacture, laying and operation, nor should it replace design codes of practice from the engineer's desk. Emphasis is on the design of large Pipelines as opposed to industrial and domestic piping which are covered in other pub1 ications. Although directed at the water engineer, this book will be of use to engineers involved in the piping of many other fluids as well as solids and gases. It should be noted that some of the designs and techniques described may be covered by patents. These include types of pre- stressed concrete pipes, methods of stiffening pipes and branches and various coatings. VI The S.I. system of metric units is preferred in the book although imperial units are given in brackets in many instances. Most graphs and equations are represented in uni versa1 dimensionless form. Worked examples are given for many problems and the reader is advised to work through these as they often elaborate on ideas not highlighted in the text. The algebraic symbols used in each chapter are summarized at the end of that chapter together with specific and general references arranged in the order of the subject matter in the chapter. The appendix gives further references and standards and other useful data. PREFACE TO SECOND EDITION The gratifying response to the first edition of this book resulted in small amendments to the second impression, and some major alter- ations in this new edition. The chapters on transport of solids and sewers have been replaced by data more relevant to water engineers. Thus a new chapter on the effects of air in water pipes is included, as well as a chapter on pumping systems for water pipelines. The latter was reviewed by Bill Glass who added many of his own ideas. There are additions and updating throughout. There is additional information on pipeline economics and optimum diameters in Chapter 1. A comparison of currently used friction formulae is now made in Chapter 2. The sections on non-circular pipe and partly full pipes and sewer flow are omitted. These are largely of interest to the drainage engineer and as such are covered in the author’s book ‘Stormwater Hydrology and Drainage’ (Elsevier, 1981). A basic introduction to water hammer theory preceeds the design of water hammer protection of pumping and gravity lines in Chapter 4. The sections on structural design of flexible pipes are brought together. An enlarged section on soil-pipe interaction and limit states of flexible pipes preceeds the design of stiffened pipes. Although some of the new edition is now fairly basic, it is recognised that this is desirable for both the practicing engineer who needs refreshing and the student who comes across the problem of pipeline design for the first time. VIII PREFACE TO THIRD EDITION Recent research in cavitation and flow control has prompted additional sections on this. There are also new sections on supports to exposed pipes and secondary stress. Additional references and a new layout make up this edition. Some sections appearing in previous editions, noteably on pipe network systems analysis and optimization have been ommitted as they were considered more appropriate in the alJthOr’S parallel book ‘Pipeflow Analysis’ by the same publisher. IX ACKNOWLEDGEMENTS The basis for this book was derived from my experience and in the course of my duties with the Hand Water Board and Stewart, Sviridov and 01 iver, Consulting Engineers. The extensive knowledge of Engineers in these organizations may therefore be reflected herein although I am solely to blame for any inaccuracies or misconceptions. I am grateful to my wife Lesley, who, in addition to looking after the twins during many a lost weekend, assiduously typed the first draft of this book. David Stephenson 1 CHAPTER 1 ECONOMIC PLANNING I NTRODUCT ION Pipes have been used for many centuries for transporting fluids. The Chinese first used bamboo pipes thousands of years ago, and lead pipes were unearthed at Pompeii. In later centuries wood-stave pipes were used in England. It was only with the advent of cast iron, however, that pressure pipelines were manufactured. Cast iron was used extensively in the 19th Century and is still used. Steel pipes were first introduced towards the end of the last century, facilitating construction of small and large bore pipelines. The increasing use of high grade steels and large rolling mills has enabled pipelines with diameters over 3 metres and working pressure over 10 Newtons per square millimetre to be manufactured. Welding techniques have been perfected enabling longitudinally and circumferentially welded or spiral welded pipes to be manufactured. Pipelines are now also made in reinforced concrete, pre-stressed concrete, asbestos cement, plastics and claywares, to suit varying conditions. Reliable flow formulae became available for the design of pipelines this century, thereby also promoting the use of pipes. Prior to this century water and sewage were practically the only fluids transported by pipeline. Nowadays pipelines are the most common means for transporting gases and oils over long distances. Liquid chemicals and solids in slurry form or in containers are also being pumped through pipelines on ever increasing scales. There are now over two million kilometres of pipelines in service throughout the world. The global expenditure on pipelines in 1974 was probably over 55 000 million. There are many advantages of pipeline transport compared with other methods such as road, rail, waterway and air:- (1) Pipelines are often the most economic form of transport (considering either capital costs, running costs or overall costs). (2) Pipelining costs are not very susceptible to fluctuations in 2 prices, since the major cost is the capital outlay and subsequent operating costs are relatively small. Operations are not susceptible to labour disputes as little attendance is required. Many modern systems operate automatical- lY. Being hidden beneath the ground a pipeline will not mar the natural environment. A buried pipeline is reasonably secure against sabotage. A pipeline is independent of external influences such as traffic congestion and the weather. There is normally no problem of returning empty containers to the source. It is relatively easy to increase the capacity of a pipeline by installing a booster pump. A buried pipeline will not disturb surface traffic and services. (10) Wayleaves for pipelines are usually easier to obtain than for roads and railways. (11) The accident rate per ton - km is considerably lower than for other forms of transport. (12) A pipeline can cross rugged terrain difficult for vehicles to cross. There are of course disadvantages associated with pipeline systems:- The initial capital expenditure is often large, so if there is any uncertainty in the demand some degree of speculation may be necessary. There is often a high cost involved in filling a pipeline (especially long fuel lines). Pipelines cannot be used for more than one material at a time (although there are multi-product pipelines operating on batch bases). There are operating problems associated with the pumping of solids, such as blockages on stoppage. It is often difficult to locate leaks or blockages. PI PEL I NE ECONOM I CS The main cost of a pipeline system is usually that of the pipeline 3 itself. The pipeline cost is in fact practically the only cost for gravity systems but as the adverse head increases so the power and pumping station costs increase. Table 1.1 indicates some relative costs for typical installed pipel i nes. With the economic instability and rates of inflation prevailing at the time of writing pipeline costs may increase by 20% or more per year, and relative costs for different materials will vary. In particular the cost of petro-chemical materials such as PVC may increase faster than those of concrete for instance, so these figures should be inspected with caution. TABLE 1.1 Relative Pipeline Costs Bore mm Pipe Material 150 450 1 500 PVC 6 23 - Asbestos cement 7 23 - Reinforced concrete - 23 80 Prestressed concrete - 33 90 - 150 Mild steel 10 28 100 - 180 High tensile steel 11 25 90 - 120 Cast iron 25 75 - <:,,-s, indicates not readily available. 1 unit = d;/metre in 1974 under average conditions The components making up the cost of a pipeline vary widely from situation to situation but for water pipelines in open country and typical conditions are as follows:- Supply of pipe - 55% (may reduce as new materials are developed) Excavation - 20% (depends on terrain, may reduce as mechanical excavation techniques im- prove) Laying and jointing - 5% (may increase with la- bour costs) Fittings and specials - 5% Coating and wrapping - 2% Structures (valve chambers, anchors) - 2%
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